1. Field of the Invention
The present invention relates to an information transmission device, system, and method in which handshaking is used for power-saving purposes.
2. Description of the Related Art
Sensor networks and other networks that transmit information often include battery-driven nodes that operate only intermittently and power down or ‘sleep’ when not operating, in order to extend their battery life. Since a node cannot receive transmitted information while asleep, the transmitting node must use some scheme to make sure that the receiving node is ready. One such scheme is the RICER (Receiver Initiated CyclEd Receiver) handshaking scheme proposed by Lin et al. in ‘Power-Efficient Rendez-vous Schemes for Dense Wireless Sensor Networks’ in the proceedings of the IEEE International Conference on Communications, pp. 3769-3776, 2004, in which a node with information to transmit waits to receive a signal indicating that the destination node is awake before beginning the transmission. The RICER scheme will be further described in the detailed description of the invention.
Actual networks (multi-hop networks, for example) often include both battery-powered nodes, transmission to which requires this type of handshaking, and externally powered nodes, transmission to which does not require such handshaking. A problem with use of the RICER scheme in these networks is that the RICER scheme always employs handshaking. Even in a transmission to a node that is always awake, extra signals must first be transmitted and received to confirm that the node is awake. This consumes extra power and delays the information transmission process.